Question:The number y is one-fourth of x less than the number x. Which equation represents the relationship between x and...
GMAT Algebra : (Alg) Questions
The number \(\mathrm{y}\) is one-fourth of \(\mathrm{x}\) less than the number \(\mathrm{x}\). Which equation represents the relationship between \(\mathrm{x}\) and \(\mathrm{y}\)?
1. TRANSLATE the word phrase carefully
- The phrase "y is one-fourth of x less than the number x" breaks down as:
- Start with "the number x"
- Subtract "one-fourth of x" from it
- This gives us y
- In mathematical notation: \(\mathrm{y = x - \frac{1}{4}x}\)
2. SIMPLIFY by combining like terms
- We have: \(\mathrm{y = x - \frac{1}{4}x}\)
- Rewrite x as \(\mathrm{\frac{4}{4}x}\): \(\mathrm{y = \frac{4}{4}x - \frac{1}{4}x}\)
- Combine the fractions: \(\mathrm{y = \frac{4-1}{4}x = \frac{3}{4}x}\)
Answer: D) \(\mathrm{y = \frac{3}{4}x}\)
Why Students Usually Falter on This Problem
Most Common Error Path:
Weak TRANSLATE skill: Students often misread "one-fourth of x less than x" as simply "one-fourth of x," ignoring the "less than x" part entirely.
They think: "y is one-fourth of x" → \(\mathrm{y = \frac{1}{4}x}\)
This leads them to select Choice B (\(\mathrm{y = \frac{1}{4}x}\)).
Second Most Common Error:
Poor TRANSLATE reasoning: Students interpret "one-fourth of x less than x" as "x minus one-fourth" instead of "x minus one-fourth of x."
They think: "less than x by one-fourth" → \(\mathrm{y = x - \frac{1}{4}}\)
This leads them to select Choice A (\(\mathrm{y = x - \frac{1}{4}}\)).
The Bottom Line:
The key challenge is carefully parsing the English phrase. "One-fourth of x less than x" means you start with x and subtract one-fourth OF x (not just subtract one-fourth). The word "of" is crucial—it means multiply, so "one-fourth of x" = \(\mathrm{\frac{1}{4}x}\).